Internal-combustion heater for heating air



Sept. 27, 1949.

H! J. DE N. MCCOLLUM INTERNAL-COMBUSTION HEATER FORHEATING AIR Filed Sept. 27, 1943 2 Sheet's-Sheet l SPt 27 1949- l H. J. DE N. MccoLLuM 2,482,988

- INTERNL-CQMBUSTI'UN 4HEATER -FOR HEATING AIR Filed sept. 2v.. 194s 'z sheets-sheet 2 I f Nr ga/1.9mm 01C):

Patented Sept. 27, 1949 UNITED STATES [OFFICE INTERNAL-COMBUSTION HEATERFOR HEATINGAIR n I 1 Henry J. De N. McCollum, Chicago, Ill.;

Thelma' McCollum, executrix of said HenryvJ. De N. McCollum, deceased, assigner to Stewart-Warner Corporation,l Virginia Chicago, Ill.,` a vcorporation of Application september 27, 1943,' seriallvofsoaeai (Cl. 12B- 116) Other objects and advantages will become api parent as the description proceeds.

In the drawings:V c

Fig. 1 is a longitudinaL'sectional view through a heater embodying a preferred form of my invention;

Fig. 2 is a transverse, sectional view taken on the line 2-'-2 of Fig. 1;

Fig. 3 is a transverse, sectional view taken on the line 3 3 of Fig. 1;V

`rcrimped over a retaining plate 34, provided with similar perforations 36. Filtering material "38 is confined between the retaining plate 34 and the base of 'thejcup'3l and serves to remove impurities lfrorntl'ie air passing therethrough'. This iltering m'aterialin'ay be' glass wo'ol or stainless steel Wool, or any" other suitable material.

fA Air entering the preheating chamber 22 absorbs heat from the kwalls ofj thischamber and then passes `into pipes 40 and 42 leading to the Venturi tube 44 of acarburetor 46'.' A fuel' jet 48 delivers gascline,"or' other suitable fuel, to the vthroat of the Venturi"'tube 44,`where this fuel mixes the" airl suppliedfthrough pipes 40 and 42. The mixture of 'fu'el and air` formed in the Venturi tube passesfintoan induction tube 50, having an inclined and curved end 52 located in the combus- Fig. 4 is a partial, transverse, vsectional view taken on the line 4-4 of Fig. 1; and

Fig. 5 is a partial, transverse, sectional view taken on the line 5-5 of Fig. 1.

Referring to Fig. 1, it will be seen that I have disclosed therein an internal combustion type of heater having a sheet metal casing l0 illustrated as being formed of the three sections I2|4 and I6 secured together by bolts I8, or in any other Suitable manner. The lefthand end of the casing l2 is connected to a ram or blower or other suitable source of Ventilating air and the righthand endV of the casing may lead directly into an aircraft cabin or other space to be heated,`v or may communicate with a duct system havingr a plurality of outlets in the same or different compartments.

My novel heater has a combustion air pipe 20, whose lefthand end may communicate with the interior of the section l2 of the casing Il) for receiving air therefrom, or may be connected with a separate ram or blower for supplying only combustion air. The combustion air pipe 20 delivers ,the combustion air to a preheating chamber 22 having a sheet metal wall 24 which separates this preheating chamber from a combustion chamber 26.

A ltering cartridge 28 is preferably interposed between the combustion air pipe 20 and the pre; heating chamber 22, so that the air entering this chamber is rst cleaned of all dirt` or other impurities. The cartridge 28 comprises a sheet metal cup 3i), having a base provided with per- QraLQn.- ,The free .edge efihe @up 30 is tion chamber 2B. The combustible mixture delivered to the combustion chamber by the induction tube is initially ignited by an electric igniter 54 locatedin a pocket 56 communicating with the combustion chamber at its upper and lower ends by way of passagesY 58 and 60, respectively. The righthand end of, the combustion chamber is provided with an inwardly directed flange 62, whichrserves to prevent discharge from the combustion chamber of unburned liquid fuel.v The hot products of combustion formed in the combustion chamber iiow through the opening provided by the annular flange 62 into a flared passage 64 leading to the inlet end of a heat exchanger,` indicated generally byreference character 66. This'heat exchanger comprises a pair of headers 68 and 10 and heat transfer tubes 'l2 connecting these headers. The particular design of heat exchanger shown herein forms the subject matter of my co-pending application, Serial No. 516,648, led January 1,' 1944 and now Patent No. V2,451,851 issued October 19, 1948. The hot products of combustion iiow through the passages in the tube 12 Vof thel heat exchanger and give up their heat to this heat'exchanger. These cooled products of combustion then pass into an exhaust chamber y'lll and are discharged to atmosphere through an exhaust pipe v16.

i The vexhaust chamber 'I4L is of tapered crosssection, as clearlyshown in Fig. 1 of the drawings, and has an inclined .wall 18 provided with periorations which form acoustic-couplings between the exhaust chamber 14 and a muiiling chamber 82, which is illustrated as being filled with sound absorbing material, such as stainless steelwool or glass wool. G6 is extremely efficient in removing heat from the hot products of combustion, so that the temwith v The heat exchanger perature of these gases is reduced to 250 or 300 F. before they are discharged into the exhaust chamber '14. The sound absorbing material in the muiler chamber 82 is, therefore, never exposed to a high ltemperature and this feature is of great importancein preventing deterioration of this sound absorbing material. The inclined wall 18 of the exhaust chamber 'I4 is also commorr to the muilling chamber 82 and proVidessa-.muiing chamber of varying depth, which is partieul'arly ecient in absorbing a Wide range of objectionable noises.

The Ventilating air owing through the casing" l first passes around the combustion' charnberv 26 and tapered passage 64 and absorbs some heat from the annular walls thereof. This Ventilating air then flows through an opening iltbe'nca-th the header 8 and thence upwardly between the heat transfer tubes 12.` The arrangement oi these tubes and the direction of air ow therethrough is best shown in Fig; 4', which also shows one of theV two bafll'e's 86 located on opposite sides of the tube bundle and' serving to prevent appreciable quantities of air from laypassingV the tube bundle by flowing upwardly around' theV sides thereofl The lower wall 88 of the casing section I4 is inclined upwardly, as clearly shown in Fig. 1 toV produce a smopthv ow' of Ventilating air into the lower side of the tube bundle and the upper walll 98' of. this casing section is similarly It is to be notedI that the passages in the tube 'l2 through which the products ofY combustion flow are of' smalll diameter and these small passages retard the rate of flame propagation and thus soften` any explosion whichv may take place in the heater. Furthermore, the combustionY chamber 26, passage 6H, discharge chamber 'I and. muiiiing chamber 8'2 are each of relatively small volume, so that no violent explosions of unburned gasescan occur andthe parts need not be made especially strong to withstand such heavy explosions. The design of my novel heater is such that it is` extremely quiet in operation and a small mulfling chamber 82 is sucient to absorb any undesirable noises even where the heater is operated with an exhaust pipe 'l6` ci appreciable length.

It will be understood by those skilled.' in the art that my new and improved heater may be provided with the usual thermostaticY control for cutting out the electrical igniter 54 when the heater attains normal operating temperature. It

is to be further understood that my heater may be provided with other usual or suitable controls for regulating the supply of Ventilating and combustion air and the quantity of fuel consumed in the combustion chamber. My heater may also be provided with the usual overheat controls which I have not deemed it necessary to show in the drawings.

From the foregoing description taken in con.- nection with the accompanying. drawings, it will be seenv that IV have invented a novel heater which is compact and which. may be easily and inexpensively manufactured of conventional materials utilizing conventional machinery and processes. This heater is highly ecient and is particularly suitable for heating the cabins and other enclosed Spaces of aircraft. It is to be understood, however, that my novel heater is not limited to such use and' maybe also used for general heating purposes.

While I have illustrated and described only a single embodiment of my invention, it is to be understoodthat my invention is not limited to the particular details shown and described, but may assume numerous other forms and that my invention includes all modifications, variations and" equivalents coming within the appended claims.

I'claiin:

1. A heater of the class described, comprising a burner having atubular wall, a heat exchanger connected to one end of said wall, means for supplying Ventilating air to said heat exchanger, means for supplying a combustible mixture to said burner; said burner' serving tov furnishhot products of'combustion to said' heat exchanger, means forming an exhaust'cha-mber'communicating with saidheat exchanger; said exhaust chamber having an inclined wail'spaced from said heat exchanger, and a muliler communicating with said exhaust chamber through p'erf'orations` inv said inclined wall, saidpe'r'forations forming an acoustic coupling between said mui'ller andsaidA exhaust chamber.

22 A heater of thecl'ass described', comprising a casing having one end adapted to be connected to a source of Ventilating air, said casing having an intermediate section provided with opposing inclined walls, a heat exchanger located in said intermediate section and cooperating therewith to form a Ventilating air passage transversely of said heat exchanger, means forming a combustion chamber for supplying hot products of combustion to said heat exchanger',1m`eans forming an acousti'call'y coupled t'o said exhaust chamber.

3. A heater of the class'de'scribed, comprising a casing havingl one endv connected to' a source of Ventilating air, said casing being of rectangular cross section and beingY of greater height than width',l a tubular burner located in said casing, meansfor supplying a combustible mixture to said burner a heat exchanger located in said casing and' having a rectangular tube bundle, means connecting said' burner and heat exchanger whereby products of combustion fromsaid burner flowV to said heat exchanger,` saidl heat exchanger and casing being so constructed as to direct Ventilating 'air transversely of said tube bundle, means forming' an outlet forV gases leaving said heat exchanger", and a` muler of substantially the same cross section as said heat exchanger and in communication therewith, said muler being located' in' said casing and being separated from saidl burner by said' heat exchanger.

4. A` heater of the class described, comprising a tubular casing having one end adapted to communicate withk a sourceA of Ventilating air, said casing having oifset ends and an inclined intermediate portion connecting said ends, means 7'0 forming a combustionA chamber located in said first-mentioned end, al heat exchanger located in said intermediate' portion andl sov constructed and arranged therein that the inclination of said intermediate portion directs Ventilating air transverseiyofsaid'heat exchanger, means connecting said combustion chamber and heat exchanger whereby the latter receives products of combustion from the former, and means forming an exhaust chamber and muffler connected to said heat exchanger and located in the other end of said casing.

5. A heater of the class described, comprising a tubular casing of rectangular cross-section, said casing having end portions and an intermediate portion provided with upper and lower walls inclined at an angle of less than 45 to the end portions of said casing, a heat exchanger located in said intermediate portion, said heat exchanger having a bundle of straight, heat-transfer tubes extending parallel to the axes of the end portions of said casing, the tubes of said bundle being spaced apart and so arranged that said bundle is rectangular in cross-section, said bundle having one end closely adjacent one end of one of said inclined walls and said bundle having a second end closely adjacent the opposite end of the other inclined wall, said tube bundle and one of said inclined walls forming a triangular entrance for 6 Ventilating air owing transversely of said tube bundle and said bundle and the other inclined wall forming a triangular outlet for said air, said triangular inlet and outlet flaring in opposite directions, and means for supplying hot products of combustion to said heat exchanger.

HENRY J. DE N. MCCOLLUM.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STTES PATENTS Number Name Date 467,145 Bartlett Jan. 19, 1892 752,002 Shafer Feb. 9, 1904 1,062,521 Trotter May 20, 1913 1,466,186 Pidgeon Aug. 28, 1923 1,579,599 DeForest Apr. 6, 1926 1,701,249 Wallstrom Feb. 5, 1929 1,924,209 Kilgour Aug. 29, 1933 2,101,460 Schmidt Dec. 7, 1937 2,286,856 Holthouse June 16, 1942 

